Xi:Irritant;
90-43-7Relevant academic research and scientific papers
Pd(II) complexes with ONN pincer ligand: Tailored synthesis, characterization, DFT, and catalytic activity toward the Suzuki-Miyaura reaction
Bagri, Sanjay Singh,Chaurasia, Bhaskar,Gaur, Pratiksha,Mehrotra, Ripul,Raidas, Mohan Lal,Shukla, Satyendra Nath
, (2020/08/25)
A pincer type ONN tridentate Schiff base ligand, 2-(((pyridin-2-yl)methylimino)methyl)-6-methoxyphenol, (L1) synthesized by the condensation of 4-hydroxy-3-methoxy-benzaldehyde and (pyridin-2-yl)methanamine. The ligand L1 and the new Pd(II) heteroleptic complexes of the composition [Pd(L1)(L2)]Cl, where L2 = benzimidazole, imidazole, benzooxazol or pyridine were synthesized and characterized by a set of chemical, spectrometric and spectroscopic analyses. These complexes were named 1 to 4, respectively. The FT-IR and DFT have suggested that ligand is coordinated with metal through azomethine-N and phenolic-O and arranged in square planar fashion around the metal. Correlation coefficients value between 0.995 - 0.993 shows satisfactory agreement in theoretical and experimental 1H-NMR and 13C-NMR. Benzimidazole anchored complex 1 exhibits an excellent catalytic activity. DFT calculated the energy profile diagram of the Suzuki-Miyaura reaction.
C(acyl)-C(sp2) and C(sp2)-C(sp2) Suzuki-Miyaura cross-coupling reactions using nitrile-functionalized NHC palladium complexes
?akir, Sinem,Karabiyik, Hande,Kavukcu, Serdar Batikan,Rethinam, Senthil,Türkmen, Hayati
, p. 37684 - 37699 (2021/12/09)
Application of N-heterocyclic carbene (NHC) palladium complexes has been successful for the modulation of C-C coupling reactions. For this purpose, a series of azolium salts (1a-f) including benzothiazolium, benzimidazolium, and imidazolium, bearing a CN-substituted benzyl moiety, and their (NHC)2PdBr2 (2a-c) and PEPPSI-type palladium (3b-f) complexes have been systematically prepared to catalyse acylative Suzuki-Miyaura coupling reaction of acyl chlorides with arylboronic acids to form benzophenone derivatives in the presence of potassium carbonate as a base and to catalyse the traditional Suzuki-Miyaura coupling reaction of bromobenzene with arylboronic acids to form biaryls. All the synthesized compounds were fully characterized by Fourier Transform Infrared (FTIR), and 1H and 13C NMR spectroscopies. X-ray diffraction studies on single crystals of 3c, 3e and 3f prove the square planar geometry. Scanning Electron Microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), metal mapping analyses and thermal gravimetric analysis (TGA) were performed to get further insights into the mechanism of the Suzuki-Miyaura cross coupling reactions. Mechanistic studies have revealed that the stability and coordination of the complexes by the CN group are achieved by the removal of pyridine from the complex in catalytic cycles. The presence of the CN group in the (NHC)Pd complexes significantly increased the catalytic activities for both reactions.
Homogeneous Palladium-Catalyzed Selective Reduction of 2,2′-Biphenols Using HCO 2H as Hydrogen Source
Li, Ruoling,Li, Chenchen,Yang, Wen,Zhao, Wanxiang
, p. 1605 - 1618 (2021/02/01)
An efficient homogeneous palladium-catalyzed selective deoxygenation of 2,2′-biphenols by reduction of aryl triflates with HCO 2H as the hydrogen source is reported. This protocol complements the current method based on heterogeneous Pd/C-catalyzed hydrogenation with hydrogen gas. This process provided the reduction products in good to excellent yields, which could be readily converted to various synthetically useful molecules, especially ligands for catalytic synthesis.
From the grafting of NHC-based Pd(II) complexes onto TiO2 to the in situ generation of Mott-Schottky heterojunctions: The boosting effect in the Suzuki-Miyaura reaction. Do the evolved Pd NPs act as reservoirs?
De Tovar, Jonathan,Rataboul, Franck,Djakovitch, Laurent
, p. 133 - 147 (2021/05/10)
The assumption that the real active species involved in the Suzuki-Miyaura reaction are homogeneous, heterogeneous or both is often proposed. However a lack of characterization of the true catalytic entities and their monitoring makes assumptions somewhat elusive. Here, with the aim of getting new insights into the formation of active species in the Suzuki-Miyaura reaction, a family of palladium(II) complexes bearing bis(NHC) ligands was synthesized for immobilization at the surface of TiO2. The studies reveal that once the complexes are anchored onto TiO2, the mechanism governing the catalytic reaction is different from that observed for the non-anchored complexes. All complexes evolved to Pd NPs at the surface of TiO2 under reaction conditions and released Pd species in the liquid phase. Also, this reactivity was boosted by the in situ generation of Mott-Schottky heterojunctions, opening new routes towards the design of heterogenized catalysts for their further implementation in reverse-flow reactors.
Microflowers formed by complexation-driven self-assembly between palladium(ii) and bis-theophyllines: Immortal catalyst for C-C cross-coupling reactions
Jin, Ren-Hua,Jou, Naoki,Kaikake, Katsuya,Shitara, Go
, p. 35311 - 35320 (2021/11/30)
The Pd catalyst for Suzuki-Miyaura or the other C-C coupling reactions is one of the central tools in organic synthesis related to medicine, agricultural chemicals and advanced materials. However, recycling palladium is a bottleneck for developing the extreme potential of Pd in chemistry. Herein, we established a new heterogeneous Pd catalytic system in which the catalyst is a nanopetal-gathered flower-like microsphere self-assembled from PdCl2 and alkyl-linked bis-theophyllines. The microflowers catalyzed quantitatively the reaction of aryl bromides and phenylboronic acid in aqueous media at room temperature. It was found that the reaction proceeds better in an air atmosphere than in nitrogen gas even though the Pd(ii) species employed was lowered to 0.001 mol% in the substance. Very interestingly, the microflowers could be recycled 20 times without deactivation in the C-C coupling reaction between bromobenzene and phenylboronic acid in the presence of sodium chloride. We found that the sodium chloride added played an important role in maintaining the morphology of microflowers and preventing the formation of metallic Pd particles.
Catalyst-Free Synthesis of O-Heteroacenes by Ladderization of Fluorinated Oligophenylenes
Feofanov, Mikhail,Akhmetov, Vladimir,Takayama, Ryo,Amsharov, Konstantin
supporting information, p. 5199 - 5203 (2021/02/21)
A novel catalyst-free approach to benzoannulated oxygen-containing heterocycles from fluorinated oligophenylenes is reported. Unlike existing methods, the presented reaction does not require an oxygen-containing precursor and relies on an external oxygen source, potassium tert-butoxide, which serves as an O2? synthon. The radical nature of the reaction facilitates nucleophilic substitution even in the presence of strong electron-donating groups and enables de-tert-butylation required for the complete annulation. Also demonstrated is the applicability of the method to introduce five-, six-, and seven-membered rings containing oxygen, whereas multiple annulations also open up a short synthetic path to ladder-type O-heteroacenes and oligodibenzofurans.
Catalytic SNAr Hydroxylation and Alkoxylation of Aryl Fluorides
Kang, Qi-Kai,Li, Ke,Li, Yuntong,Lin, Yunzhi,Shi, Hang,Xu, Lun
supporting information, p. 20391 - 20399 (2021/08/13)
Nucleophilic aromatic substitution (SNAr) is a powerful strategy for incorporating a heteroatom into an aromatic ring by displacement of a leaving group with a nucleophile, but this method is limited to electron-deficient arenes. We have now established a reliable method for accessing phenols and phenyl alkyl ethers via catalytic SNAr reactions. The method is applicable to a broad array of electron-rich and neutral aryl fluorides, which are inert under classical SNAr conditions. Although the mechanism of SNAr reactions involving metal arene complexes is hypothesized to involve a stepwise pathway (addition followed by elimination), experimental data that support this hypothesis is still under exploration. Mechanistic studies and DFT calculations suggest either a stepwise or stepwise-like energy profile. Notably, we isolated a rhodium η5-cyclohexadienyl complex intermediate with an sp3-hybridized carbon bearing both a nucleophile and a leaving group.
Insights into the Suzuki-Miyaura Reaction Catalyzed by Novel Pd?Carbene Complexes. Are Palladium?Tetra- carbene Entities the Key Active Species?
De Tovar, Jonathan,Rataboul, Franck,Djakovitch, Laurent
, p. 5797 - 5808 (2020/09/11)
The assumption that the real active species involved in the Suzuki-Miyaura reaction are homogeneous, heterogeneous or both is often proposed. However a lack in the characterization of true catalytic entities and their monitoring makes assumptions somewhat elusive. Here, three families of palladium(II) complexes bearing bisNHC, bispyridyl and bisphosphine ligands were synthesized in order to get new insights into the formation of active species in the Suzuki-Miyaura reaction. Their comparative catalytic study reveals that the nature of the ligands as well as their spacer lengths are pivotal parameters governing the performance. All complexes evolve to Pd NPs under reaction conditions, and an orthogonal behavior is observed for two bisNHC complexes that form homoleptic tetracarbene species. Notably, these species are presumably involved in a new catalytic modus operandi. This ligand-controlled reactivity and the formation of tetracarbene species open new routes towards the design of novel cross-coupling catalysts via the mastering of highly-active catalytic species.
Palladium Supported on Silk Fibroin for Suzuki–Miyaura Cross-Coupling Reactions
Albano, Gianluigi,Farinola, Gianluca M.,Lo Presti, Marco,Milella, Antonella,Omenetto, Fiorenzo G.,Rizzo, Giorgio
supporting information, p. 6992 - 6996 (2020/11/30)
Silk fibroin supported Pd (Pd/SF) has been prepared and used as catalyst in Suzuki–Miyaura cross-coupling reactions in water/ethanol (4:1 v/v) mixture. The reactions proceed rapidly with aryl iodides and boronic acids with different electronic properties using low metal loading (0.38 mol-%). Pd/SF exhibits better recyclability compared to other biopolymer-supported Pd catalysts, up to nineteen cycles without loss of activity.
Synthesis of Enaminone-Pd(II) Complexes and Their Application in Catalysing Aqueous Suzuki-Miyaura Cross Coupling Reaction
Fu, Leiqing,Cao, Xiaoji,Wan, Jie-Ping,Liu, Yunyun
, p. 254 - 258 (2020/01/25)
A series of Pd(II)-enaminone complexes, termed Pd(eao)2, have been synthesized and characterized. The investigation on the catalytic activities of these new Pd(II)-reagents has proved that the Pd(eao)2-1 possesses excellent catalytic activity for the Suzuki- Miyaura cross coupling reactions of aryl bromides/chlorides with aryl/vinyl boronic acids in the environmentally benign media of aqueous PEG400 at low loading (5 mol‰). The superiority of this Pd(II)-reagent to those commercial Pd(II) and Pd(0) catalysts in catalyzing the reactions has been confirmed by parallel experiments. What's more, Pd(eao)2-2 has been found as a practical catalyst for the homo-coupling reactions of aryl boronic acids.
